coanda effect
Found this on MS Encarta.
The theory would explain the flat plate phenomenon. It makes a very straight forward parallel between holding your hand out of a moving car window and adjusting the angle at which you present your hand to the wind. The speed through the air is also an important factor for the reaction force placed against the wind thus producing an "equal and opposite reaction" of the airfoil 'upwards'. It then goes on to describe how the bernoulii principle is an effect of lift but not its cause.
From this I understand that airfoils are given various shapes depending on the task at hand. A large slow moving heavy aircraft would benefit from having a concave undersurface of the wing (slats and flaps contribute to this)as this effectively acts like a parachute. With a forward force still being applied the a/c goes up (just like the boat towing parachute rides you get at the beach). To preserve this effect throughout flight, the a/c's wing incidence angle is usually set at around 4 degrees up w.r.t.o the horizontal thus always having a downward force.
Yes, there is low pressure above the wing and this is caused by faster moving air above - but has very little contribution to overall lift of the a/c. The camber of the wing is there to minimise drag as a flat plate would have severe vortices, hence drag above it.
Have a look at the Encarta CD. They quote 'Boeing' as their information source. There is an interesting diagram/video that goes along with it.
FJ